(1) Field of the Invention
The present invention pertains to a manually operated liquid foaming dispenser. Specifically, the invention pertains to a manually operated pump that is attached to the top of a bottle of liquid and is manually vertically reciprocated to dispense the liquid from the container as a foam. The pump includes a liquid pump chamber and an air pump chamber that respectively pump liquid and air under pressure to a discharge passage of the pump where the liquid and air are mixed, generating the foam dispensed from the pump.
(2) Field of the Invention
Manually operated liquid dispensers that dispense liquid as a foam are known in the prior art. The most well known of these types of dispensers are manually operated trigger sprayers that pump liquid from a bottle container attached to the trigger sprayer and dispense the liquid as a foam that is discharged from the trigger sprayer. The dispensing nozzle of this type of trigger sprayer typically discharges the liquid as a spray toward an obstruction that is vented to the atmosphere. The spray hitting the obstruction mixes the liquid spray with the air of the atmosphere producing the foam that is discharged from the trigger sprayer.
The typical trigger sprayer that discharges a foam is constructed of a sprayer housing containing a pump chamber, a liquid supply passage, and a liquid discharge passage. The liquid supply passage communicates the pump chamber with the liquid contained in the container attached to the trigger sprayer. A pump piston is mounted in the pump chamber for reciprocating movement between charge and discharge positions. A trigger is attached to the sprayer housing and is connected to the pump piston for moving the pump piston. The pump chamber also communicates with the liquid discharge passage which extends from the pump chamber to the discharge nozzle of the trigger sprayer.
A first check valve assembly is positioned between the pump chamber and the liquid supply passage. The first check valve allows liquid to travel through a dip tube and the liquid supply passage into the pump chamber when the pump piston is moved to the charge position, and prevents the reverse flow of liquid from the pump chamber when the pump piston is moved to the discharge position. A second check valve is usually positioned in the discharge passage between the pump chamber and the discharge nozzle. The additional check valve assembly allows the flow of liquid from the pump chamber through the discharge passage to the discharge nozzle when the pump piston is moved to the discharge position, but prevents the reverse flow of liquid and/or air when the pump piston is moved to the charge position.
The basic construction of the foaming liquid trigger sprayer described above is well suited for dispensing liquids where the desired foaming of the liquid is marginal, for example in dispensing foaming liquid kitchen cleaners or bathroom cleaners. However, the foaming trigger sprayers cannot produce a more dense foam such as that of shaving cream.
To produce a more dense foam such as that of shaving cream from a liquid dispenser requires that both the liquid and air being mixed by the dispenser be under pressure. This requires that the manually operated foaming dispenser include both a liquid pump chamber and an air pump chamber. The addition of the air pump chamber to the manually operated dispenser increases the number of component parts of the dispenser. The air pump chamber must also have an air pump piston that moves between the charge and discharge positions in the air pump chamber to draw air into the chamber and force air under pressure from the chamber. In addition, the air pump chamber must also have a check valve assembly that allows the air of the exterior environment of the dispenser to flow into the air pump chamber when the air pump piston is moved to the charge position and prevents the flow of air from the air pump chamber to the exterior environment when the air pump piston is moved to the discharge position. A second check valve assembly is also needed to control the flow of pressurized air from the air pump chamber to the discharge passage when the air pump piston is moved to the discharge position, and to prevent the reverse flow of air from the discharge passage to the air pump chamber when the air pump piston is moved to the charge position. These additional component parts required by this type of liquid foaming dispenser significantly increase manufacturing costs.
The liquid foaming dispenser of the invention overcomes disadvantages of prior art foaming dispensers having both a liquid pump chamber and an air pump chamber by reducing the number of component parts required by the air pump chamber. The liquid foaming dispenser is basically comprised of a pump housing comprising the liquid pump chamber at the bottom of the housing and a coaxial air pump chamber above the liquid pump chamber. The air pump chamber is open at its top. A container cap is provided at the top of the pump housing. A dip tube extends downwardly from the liquid pump chamber at the bottom of the pump housing. With the container cap attached to a container of liquid, the dip tube extends downwardly into the liquid.
A pump plunger is assembled into the pump housing from the top of the housing. The pump plunger has a liquid pump piston at its bottom that is inserted through the pump housing into the liquid pump chamber. A spring is positioned between the bottom of the liquid pump chamber and the liquid pump piston. An air pump piston is also provided on the pump plunger just above the liquid pump piston. The air pump piston is positioned in the air pump chamber with the liquid pump piston positioned in the liquid pump chamber. A dispenser head is provided at the top of the pump plunger. A liquid discharge passage extends through the center of the pump plunger from the liquid pump piston to the dispenser head. A liquid mixer or screen is positioned in the liquid discharge passage in the dispenser head.
In addition, three check valves are positioned along the length of the liquid discharge passage in the pump plunger. One check valve controls the flow of liquid into the liquid pump chamber and prevents the reverse flow. The second check valve controls the flow of liquid from the liquid pump chamber to the discharge passage and prevents the reverse flow. The third check valve controls the flow of air from the air pump chamber to the discharge passage and prevents the reverse flow.
The third check valve that controls the flow of air out of the pump chamber into the discharge passage and prevents the reverse flow of air from the discharge passage into the pump chamber is a resilient tube valve. The tube valve engages against the interior surface of the liquid discharge passage. Valve openings in the pump plunger communicate the exterior surface of the tube valve with the interior of the air pump chamber. The novel construction of the tube valve permits the flow of air under pressure from the air pump chamber to the discharge passage and prevents the reverse flow of air from the discharge passage to the air pump chamber. The tube valve is the only valve that controls the flow of air into and out of the air pump chamber, eliminating the additional valve present in prior art foaming dispensers that mix liquid and air under pressure.
The air pump chamber of the invention has a cylindrical interior surface with a first, upper section and a second, lower section. The interior diameter of the air pump chamber first section is slightly larger than that of the air pump chamber second section. In addition, the air pump piston exterior surface has a first section and a second section. The exterior diameter of the second section of the exterior surface is larger than the exterior diameter of the first section of the exterior surface. The exterior diameter of the second section of the air pump piston exterior surface is also larger than the interior diameter of the second section of the air pump chamber interior surface, but is smaller than the interior diameter of the first section of the air pump chamber interior surface. Thus, when the pump plunger is manually depressed downwardly moving the liquid pump piston and the air pump piston toward their discharge positions in their respective liquid pump chamber and air pump chamber, the second exterior surface section of the air pump piston will engage in sealing contact with the second section of the air pump chamber interior surface, pressurizing the air in the air pump chamber. The pressurized air eventually opens the tube valve and is discharged into the liquid passage where it mixes with the liquid being discharged from the liquid pump chamber. On the reverse direction of the pump plunger where the liquid pump piston and air pump piston are moved toward their charge positions, the second section of the air pump piston exterior surface still engages with the second section of the air pump piston interior surface for a portion of the pump plunger movement to produce a vacuum in the air pump chamber. However, when the air pump piston reaches its charge position, the second section of the air pump piston exterior surface is positioned inside the first section of the air pump chamber interior surface where it disengages from the air pump chamber interior surface. This allows the vacuum produced in the air pump chamber to draw in air from the exterior environment of the dispenser into the air pump chamber. This venting of air into the air pump chamber is accomplished without the need for an additional check valve.
Thus, the liquid foaming dispenser of the invention provides the mixing of the liquid and air under pressure in the liquid discharge passage to produce the desired foam. However, the construction of the dispenser eliminates a valve assembly from the air pump chamber that is required in prior art foaming liquid dispensers of this type. The reduced number of component parts of the dispenser of the invention allows it to be manufactured more economically, overcoming the disadvantages associated with prior art liquid foaming dispensers of this type.